1) There's very little money for writers anymore, except the extremely successful
2) Travel writing golden age was when the world was exotic and hard to visit - but now we're saturated in travel TV, cheap flights, blogging and especially Instagram posts. If you want to see what the world looks like somewhere, you can get a pretty good idea from the internet. VR tourism if it happens will only make this worse.
3) Finally, globalisation has worn down the exoticness of places. Everywhere has a McDonald's. And we're heading into a time when the pendulum of public opinion has swung against the foreign. How can you sell travel writing to a Brexit market?
(The author has reminded me of Patrick Leigh Fermor, whose Words of Mercury I need to finish.)